Field evaluation of Beauveria bassiana and novaluron alone and combined, versus conventional insecticides to control Lygus lineolaris in cotton

Authors: Portilla, Maribel; Little, Nathan; Elkins, Blake; Allen, Kerry; Du, Yuzhe

Submitted to: Agricultural Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2026
Publication Date: 3/5/2026
Citation: Portilla, M., Little, N., Elkins, B.H., Allen, K.C., Du, Y. 2026. Field evaluation of Beauveria bassiana and novaluron alone and combined, versus conventional insecticides to control Lygus lineolaris in cotton. Agricultural Sciences. 17(3):179-198. https://doi.org/10.4236/as.2026.173012.
DOI: https://doi.org/10.4236/as.2026.173012

Interpretive Summary: Efforts to identify native microbial pathogens as alternatives for managing tarnished plant bug (TPB) have increased within integrated pest management (IPM) programs, supporting the Secretary of Agriculture’s priority to “Increase Profitability of Farmers and Ranchers.” This work builds on previous studies using the entomopathogenic fungus Beauveria bassiana, which has been tested alone and in combination with insecticides for controlling various insect pests giving growers possible alternative in pest control. Over a two-year period, this study evaluated the insect growth regulator (IGR) Novaluron applied alone, Novaluron combined with the NI8 strain of B. bassiana, and the NI8 strain alone, comparing these treatments with conventional insecticides used individually or in tank mixes with different modes of action. Treatment performance was measured using cotton lint yield and TPB density. Because insecticides and biopesticides act on different tissues and life stages of TPB, their physiological effects influence lint yield, the primary indicator of TPB damage. Mortality from Novaluron alone, Novaluron + B. bassiana, or single insecticides was generally lower than mortality from combinations of organophosphates, pyrethroids, and IGRs; however, cotton yield from the Novaluron + B. bassiana treatment was comparable to yields achieved with conventional insecticides.

Technical Abstract: The efficacy of a native strain of Beauveria bassiana (Bb) (Balsamo) Vuillemin applied alone, in combination with the insect growth regulator (IGR) Novaluron, and alongside various synthetic insecticides was evaluated for its ability to suppress populations of tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois), and its impact on cotton yield. TPB suppression differed significantly among treatments, with plots treated with bifenthrin + Novaluron + acephate showing the greatest reduction across both years. No significant differences were observed between single or dual tank-mixed synthetic insecticides (imidacloprid, sulfoxaflor, or bifenthrin + Novaluron) compared to Novaluron alone or Novaluron + Bb, except for imidacloprid when the second application occurred seven days after the first.Control plots and those treated with Bb alone consistently exhibited the lowest TPB suppression across all evaluation periods, regardless of spray timing or year. This trend was reflected in cotton lint yield per harvested plot, where Bb alone (411'±'230 and 533'±'58 kg/ha) did not differ significantly from the control (487'±'152 and 446'±'42 kg/ha), representing the lowest yields among treatments in 2018 and 2019, respectively. No significant differences in lint yield were observed among plots treated with synthetic insecticides (919'±'250 and 1178'±'38 kg/ha), Novaluron alone (919'±'265 and 882'±'29 kg/ha), or Novaluron + Bb (899'±'105 and 1061'±'46 kg/ha) across both years.